Step 1 :\(P(\text{exactly 1 red}) = P(\text{RRW or WR or BR}) \)
Step 2 :\(P(\text{RRW}) = P(\text{R})^2 \cdot P(\text{W}) \)
Step 3 :\(P(\text{WR}) = P(\text{W})^2 \cdot P(\text{R}) \)
Step 4 :\(P(\text{BR}) = (1 - P(\text{W}) - P(\text{R}))^2 \cdot P(\text{R}) \)
Step 5 :\(P(RRW) = (\frac{3}{10})^2 \cdot \frac{5}{10} \)
Step 6 :\(P(WR) = (\frac{5}{10})^2 \cdot \frac{3}{10} \)
Step 7 :\(P(BR) = (1 - \frac{5}{10} - \frac{3}{10})^2 \cdot \frac{3}{10} \)
Step 8 :\(P(RRW) = (\frac{9}{100}) \cdot \frac{1}{2} \)
Step 9 :\(P(WR) = (\frac{25}{100}) \cdot \frac{3}{10} \)
Step 10 :\(P(BR) = (\frac{4}{100}) \cdot \frac{3}{10} \)
Step 11 :\(P(RRW) = \frac{9}{200} \)
Step 12 :\(P(WR) = \frac{75}{1000} \)
Step 13 :\(P(BR) = \frac{12}{1000} \)
Step 14 :\(P(\text{exactly 1 red}) = P(RRW) + P(WR) + P(BR) \)
Step 15 :\(P(\text{exactly 1 red}) = \frac{9}{200} + \frac{75}{1000} + \frac{12}{1000} \)